Telephone system.



H. P. CLAUSEN.

TELEPHONE SYSTEM.

APPLICATION mm Mm. 1. m7.

Patented. J 1113 2, 1918.

HENRY .E'. ()LAU-SEN', 0F MOUNT VERNON, NEVT YOHK. A$SIGNOR 'IO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEN YORK.

TELEPHONE SYSTEM.

Application filed August 1, 191?.

[a all w/wm it may concern:

Be it known that I, HENRY P. CLAUSEN, a citizen of the United States, residing at Mount Vernon, in the county of /Vestchestor and State of New York, have invented certain new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates'to telephone systerns involving the use of mechanical switching apparatus for establishing connections between subscribers lines.

In particular it pertains to means whereby a thorough and eflicientsupervision of the traflic handled by such a system may be readily had. Where the number of subscribers lines is sufficiently large to warrant the employment of selector as well as con nector switches, it is the generalpracticetoconnect the trunk terminals of each access point in a selector level to the corresponding terminals in the same level of other selectors. Likewise the terminals of all the levels are multipled throughout the group. The number of access points per level of the selector switch is governed largely by the volume of trafiic in the particular system involved, but as an arbitrary figure we will assume that, with a proper and adequate distribution of lines, a ten per cent. provision will be suiticient to take care of the maximum nu'inber of simultaneous calls. This means that for each level of the selector there will be ten access points, each multipled to other switches as above observed, and each multiple leading to a connector. There will then be ten connectorsper level of the selector switch, each connector having access to 100" subscribers lines. so that any call coming into this particular group oi 100 lines'must be extended overthat group of trunks which comes from the same level of the selector switches.

It frequently is the case that. due-to an inaccurate knowledge of the volume of traftic over each line, or owing to conditions which vary the volume of trallic over a certain group 0. lines, one or more groups of switches may become congested to such an extent thatsuch group or groups will not be capable of handling the tralliv. (lu the other hand, in all probability other groups will contain less busy lines uml the perce ntageof switches llll fil'fllng them servu-e 1s greater than is real ya necessary. 'lihis is Specification of Letters Patent.

Patented uly 2, 1918..

Serial No. 183,873.

It is therefore an object of this invention to provide means at the selector switches so that an attendant will be immediately apprised when a certain group of trunks in the system is becoming overloaded due to the large amount of tratllc it is called upon to handle. With this knowledge in mind and by means of certain provisions associated with the connector switches. which also forms a part of this invention, he will be able to isolate the abnormally busy lines down to the particular small group or groups of subscribers lines. The undesirable condition may thereupon be quickly relieved by merely shifting a portion of the lines to less busy groups.

Systems heretofore proposed for the tratways the uncertainty as to whether a sufli cient number are lost to warrant a redistr1-- bution of the lines served by that particular group of trunks. In accordance with the present invention means are provided whereby an exact record is obtained of the number of calls that fail to secure service over any group of trunks in the system, due to all trunks of such group being busy at the time the call was made.

in the drawing accompanying this specification, and from a study of which the objects and advantageous features of this invention will become readily apparent, there is shown diagrammatically the switches and apparatus used for setting up a connection between two subscribers lines.

Assume the subscriber whose substation ci 'uipuienl is illustrated schematically at 1 wishes to placehimselt in communication with the r-llllSOl'll)0l' at station 2. Upon the removal of his receiver a circuit is closed in the well known manner to operate a finder or other switcl'i to place its brushes 3, 4 and station 1, terminal 6 and brush 3, trunk conthe called substations number.

vductor 11, upper armature and back contact of relay l0, right-hand winding of relay 9 to ground. Relay 9 energizes and attracts its armature, thereby establishing a circuit from ground, armature and front contact of relay 9, Winding of slow release relay 13 to battery, and in which circuit said relay be comes energized. The foregoing operations have all occurred in a brief space of time due to the removal of the calling partys receiver, and before any impulses are sent.

The sender dial .14 is now manipulated to impress upon the line a series of impulses corresponding in number to the first digit of This series comprises the grou selecting impulses which, ina system utilizing only first selectors, such as the one chosen to illustrate the preseiit invention, operate the selector to position its brushes in proper relation with the particular trunk group having access through succeeding connectors to the group of say 100 subscribers lines in. which the de- The brushes 15, 16 and 17 of the selector are elevated into proper relation with said trunk group level by means of a primary steppingmagnet P M which is actuated at each retraction of the relay 9 as the impulses are sent out by the sender 14. The circuit for P M leads from ground, armature and back contact of relay --9, conductor -18, contact and lowermost lit armature of relay 10, conductor 19, inner armature and front contact oi relay 13, slow release relay 20, magnet P M to battery and ground. At its outer armature and contact,

theslow relay 13 puts a ground on the terminal 8 and all of its multiples at the finder or other preliminary switches. This ground is projected over the conductor 2'l.

During the primary or group selecting series of impulses the selector brushes 1.5, 16

and -17 are brought to a point opposite the level of trunk, terminals of trunks having access through succeeding connectors to the group of lines of which the desired subscribers line 2 is one, and which level of trunk terminals is shown as the uppermost in the figure. l

At the time the relay 20 was energized,

when relay 9 retracted its armature in response to the first impulse, it closed a circuit for the relay 22 from ground, front contact and armature of relay 20, conductor 23. Winding of 22 to battery and ground. Relay 22 attracted its armature and thereby locked up, as soon as the brush shaft had taken its first step and closed the oft-normal contacts 0 N, over a circuit from battery, Winding of 22, front contact and armature of 22, conductors 24 and 25, contact and right hand armature of secondary stepping magnet, S M, conductor 26, oil-normal springs 27 and 28, conductor 21 to ground at the outer armature and contact of relay 13. The relay 20being slow to release does not retract its armature at this time, but maintains it in its actuated position to hold a break point in the circuit ofmagnet S M, as will presently appear, until after the last impulse of the series has been transmitted.

At the termination of said impulse series and when relay 9 holds its armature attracted for a suflicient period of time, relay 20 retracts its armature and closes at its back contact a circuit for S M as follows: free pole of battery, winding of S M, left armature and contact of S M, back contact and armature'of relay 20, conductor 23, front contact and armature of relay 22, conductors 24 and 25, contact and right-hand armature of S M, conductor 26, off-normal springs 27 and 28, conductor 21 to ground at the outer armature and contact of relay 13. The secondary, stepping magnet S M energizes in this c'ir-' cult and steps the selector brushes 15, 16 and 17 onto the first set of trunk terminals inthe selected level.

Assume, for example, that the trunk represented by the first set of terminals, and. that 'all other trunks preccdingTthe trunk 29, 30, 31, are busy at the time. bus, when magnet S M gives the selector brushes their first step, and. at the same time interrupts its own circuit as well as that of relay 22, a new circuit will be immediately substituted "for relay 22 before the same has time to retract its armature. Such circuit is traceable from ground, contact and outer armature of a relay corresponding to relay 32 of the connector shown in the figure, but individual to the particular connector associated with the first trunk inthe level a test conductor corresponding to 31, test brush 17, conductor: 24:, armature, front contact and wmdm of,

magnet is again energized and advances the.

brushes onto the next set of trunk terminals,

and, so on until said brushesvfin'ally make contact with the terminals of an idle trunk,

which, as assumed in the present instance, is the trunk 29, 80, 31.

Since the connector toxwhich thistrunk leads is idle, its associated relay 32 will be deener 'izcd and consequently no circuit will be esta lished for the relay 22. Thereupom the relay 22 retracts its armature and 0116' '1 the circuit of S' M, bringin the selector brushes to rest on the idle trun A circuit 1S also closed for cutofi relay 10 r from free pole of battery, winding of 10, conductor 33, back contact and armature of relay 22', conductors 24 and 25, contact and armature of S M, conductor 26, oil-normal springs 27 and 28, conductor 21, to ground at the outer armature and contact of relay l3. Relay 10 by attracting its armatures extends the trunk conductors l1 and 12 to the brushes l5 and 16, and thence over the trunk 29, 30, to the connector switch shown in the figure.

Immediately that the relay 10 is actuated, a circuit is completed for the line relay 34 of theconnector switch, traceable from free ole of battery, right-hand winding of 3i, ack contact and inner lower armature of reverse current relay 35, trunk conductor 30, brush 16, front contact and inner lower armature of relay 10, trunk conductor 12, brush 4., terminal. 7, over the loop of substa tion 1, terminal 6, brush 3, trunl; conductor 11, upper armature and front contact of relay l0, brush 15, trunk conductor 29, upper armature and back contact of relay 35, the

left-hand winding of relay 34 to ground.

Relay 3% on attracting its armature closes a circuit for slow release relay 32, from ground, armature and front contact of relay 34., winding of 32 to the tree pole of battery.

It is obvious that upon the energization of relay l0 circuit for the selector line relayv 9 is interrupted, permitting the same to retract its armature, which in turn opens the circuit of relay 13 and allows the latter to also release its armatures' When. the outer arn'iature of relay 13 retracts, ground is removed trom the previously traced circuit of relay 10. But since relay 13 is slow torelease, a new circuit for relay lOis completed at the armature of relay 3.2 before relay 13 has timeto deenergize. :Such tlrcuit may be followed from ground, contact and outer armature of relay 32, test trunk 31, test wiper l7, conductor 2%, armature and back contact of relay 22, conductor 33. winding of relav 10 to battery and ground. 3

At the outer armature of relay a l ground 15 also placed upon the multiple test terminals of other switches in the group so that no other selector will be able to seize the trunk 2.9, 30, 31.

The apparatus is now in condition to re ccivc the second or tens series of impulses. and upon the transmission of this series and in response thereto the relay 3 actuated. At each retraction oi the armature'of relay I'lla circuit is (.(lll'lPh-lt'tl from ground. armature and back contact of relay 34'. inner a rma'turc and front contact of relay 32. slow re-lcasc relay 36,. primary stepping imwnet P M; contact and side-switch arm Si in position- 1. to ballery. lilagnet l M thus being cncrgrizcd at each impulse steps the connector brush shaft 35 and its associated brushes up to the level of contacts containing those of the called line. Relay 36 also energizes in this circuit, and being slow to release retains its armatures while the impulses are being sent.

At its outer armature relay 36 completes a circuit for the private magnet 39, from ground, outer armature and contact 40 ot relay 36, conductor 41, magnet 39, to battery the side switch is stepped into position Before describing the operation of the connector in response to the last or units impulses, whereby it places llZS- brushes upon the terminals of the desired line, itwill be well to consider at this point the adaptation of certain features associated with the connector apparatus, and by means of which the aforementioned objects are attained. It was stated hereinbefore that an attendant at the central station after having been informed byfmeans of certain instrumentalitics associated with the selector switches (later to be explained) of the abnormally busy condition of any particular group or groups of trunks, could thereupon imme diately ascertain the particular small group of, say ten subscribers lines that are responsible for this condition.

In. accordance therewith arrangement is made so that a record may he obtained of every call made into any group of lines rep resented by a level of terminals at the connector switch. To this end each connector is provided with a separate vertical row of terminals, one terminal for each level of line terminals, and diagrannnaticaliy illustrated in the figure as being below the line terminals banks. .Iach brush shaft. as the shaft 38. is provided with a sup 'ilen'lcntal brush. as the brush 42. which is arranged tonipc over said vertical row of terminals while the brush shaft is participating in its primary or elevating motion. Each of the terminals "of this row may be conveniently mnlt-i plcd to other and. corresponding terminals throughout the group of connector switches. Each of said multiples will then be connected to a registering magnet 43. which, through the agency of apawl and ratchet operated counting wheel 44, produces a record every time it becomes energized. Obviously. there will be a registering magnet for each level terminals in the connector group, or in other words. tor each small group of lines.

Returning: now to the point "where the ens impulses had ,lpccn sent to step the connector die shaft 38 and its associated brushes 4:5, 46, 47, 42 up to the proper level, it will be seen terval that the connector brushes are at rest and prior to the transmission of the last series of impulses from the calling station. At such time, the supplemental brush 42 will be resting on the particular terminal corresponding to the level opposite which the line wipers are positioned. Therefore, when relay 36 denergizes a circuit is closed from ground, armature and front. contact of relay 34, conductor 48, contact and inner armature of relay 36, conductor 4:9, contact and sideswitch arm 50 in position 1, conductor 51, brush 42, to the registering magnet 43, and thence to battery and ground. The magnet 43 is energized and operates its armature before the private magnet has time to pass switch-arm 50 out of position 1, the circuit of said private magnet 39,. as above noted, being also interrupted upon the denerg'izm tion of slow release relay 36. Therefore, whenever a call is made to any line whose terminals appear in any level of a group of connector switches, with which level a recording magnet 43 is associated, a record of such call will be made. 1

By this time the subscriber at station 1 is ready to operate his dial for the units or final digit of the called number. As before, the relay 3% vibrates its armature in response to these impulses, and at each retraction thereof the icilowing circuit is closed: ground, armature and back contact of relay 3%, inner armature and front contact of relay 32, 'relay 36, contact and outer left-hand armature of relay 52, secondary magnet 55' M, side switch arm in positien ybo battery and ground in this manner the magnet S M steps the brushes 45, 46, 47, over the selected level and v brings them to rest on the terminals of the desired line.

If at this time the'cailcd line is busy a guarding ground will be present on its test terminal. The circuit affording this busy condition will extend from ground, the side switch arm and its third contact corresponding to 53, of" the connector which is occupying the line, over a conductor correspond ing to 54, to the multiple test terminal of the busy line, and thence to the test brush at of the connector shown in the drawing, conductor 54;, side-switch arm. 53 in position 2, conductor 55, contact 5'6, winding of relay I 52, conductor 57, contact at) of relay 36, conductor 41, private magnet 39 to battery and ground. i

ltwill be seen that the contact ll), being of a make-betore-break character, closes its connection with conductor 57 before breaking engagement with the outer armature of relay 36.. Hence if the calld line is bus e ground will he suhe' over the circuit just traced to take the place of the ground previously provided by the outer armature of relay 36, which retracts at the end of tho final series of impulses. The private magnet 39 is thus retained in its energized condition to prevent the side switch from advancing into position 3.

At the same time and in the same circuit, the relay 52 energizes and attracts its armatures. At the right-hand armature and make-before-break contact of relay 52 a ground is substituted at the off-normal spring 58 for the ground at the connector test multiple to maintain the magnet 39 energized. The oilf-normal spring 58 is closed at this time.

At its inner left-hand armature, the relay 52 establishes a circuit from ground, the secondary Winding of the busy-back apparatus 59, inner annature and contact of ire-- of the connector line relay 34. Relay 32 is dei nergized and releases its armaturcs.

The following release circuit may now be traced: ground. armature and back contact of role 34 inner armature and. back contact of relay off-normal spring 63, which closed on the first primary step, rclease magnet R M to battery and ground. Release magnet R M operates to restore the connector switch to normal position. The retraction of its armatures by relay 32 also severed the previously traced holding' circuit for the cut-off relay 10. Relay 10 upon de'c'ncrgizing closes the following release circuit for the selector switch: ground, armature and back contact of relay 9, conductor 18, contact and lower armature of relay 10, conductor 19. inner armature and back contact of relay 13, off-normal springs 64 and 65, release magnet R M, to battery. The selector switch is thereby returned to normal.

If the called line is idle, no. ground is present on the test multiples to hold, the private magnet 39 energized when relay 3G releases. Private magnet 39 therefore dcenergizes and allows the side switch to advance to po ion 3.

its side-switch arm 37 goes into its third position. a circuit is closed from free pole of battery. side-switch arm 37, conductor (56, right-hand armature and contact of ringing; cut-oft relay 67, conductor (58, ringing relay narrate 69, interrupter 70, to ground. The interrupter 7O alternately opens and closes this circuit. and at each closure the relay (39 attracts its armatures to project ringing cnrrent over the called line. The ringing circuit is traceable from the ringing source conventionally shown at 71, front contact and upper armature of relay 69, line wiper 45, through the ringer of substation 2, line Wiper 16, lower armature and front contact of relay 69, to ground.

Upon the called subscriber removing his receiver a circuit is closed from battery, upper Winding of relay 35, upper armature and contact of magnet 39, back contact and lower armature of relay 69, at the time the brush of interrupter 7 0 rests on an insulatin segment, line wiper 46, over the loop of su station 2, line Wiper l5, upper armature and back contact of relay 69, lower armature and contact of magnet 39, lower Winding" of relay 35 to ground. Relay 3-5, at its lower armature closes a circuit from ground, sideswitch arm 53, in position 3, conductors 5i and 72, lower armature and contact of relay 35, winding of relay 6'? to battery and ground. Relay 67 energizes and at its left armature closes a locking circuit independent of the armature of relay 35, and at its righthand armature interrupts the previously traced circuit of the ringing" relay 69.

With sid-e-switch arms 63. and 73 in their third positions a talking connection is completed between the calling and called substations. Sidoswi'inh arm 53 places a guarding ground potential on the test multiples of all connectors in the group, over the conductor 554i and test Wiper 47. At the tcrminw tion of the conversation, the calling subscriber by hanging up his receiver restores the apparatus as hereinbefore described.

From the foregoing description the method of procedure and operation of setting up a connection, in the particular system chosen for"illustration, will be clearly understood by those skilled in the art.

A consideration or" the means employed by the present invention for ascertainingthe load or amount of traffic that any group of selector trunks is handling will no xv be given. The above description of; the extension of a connection between the substations l; and 2 was, of course, based upon the assumption that at least one selector trunk of the trunk grouphaving access to the group of lines to which substation 2 is individua was idle at the time the call was made. If at such time, however, all trunks of this group are engaged, the selector switch in its secondary trunk hunting movement will find a busy ground, as before explained, on the test terminal corresponding to each trunk access point throughout the level. The brushes 15, 16, 17 are thereforestepped over the en tire level, and upon movingoil the last trunk contacts the test brush 1'? steps onto a terminal of an additional vertical row of terminals. I

From this auxiliary terminal a conductor 74 leads to a registering magnet '75, similar to the registering magnet 43 above described. A circuit is now traceable from free pole of battery, magnet 75, conductor 74, test brush 17, conductor 25, contact and right-hand armature of S M, conductor 26, ofi-uornial w springs 27 and 28, to ground at the outer armature and contact of relay 13. Registering magnet 7 5 thereby energizes and registers one count on the device 76.

As explained in connection with the registering system associated with the connector switches, each one of these auxiliary terminals will be multipled level by level to similar and corresponding terminals in other selector switches, and a registering device like the one shown will be connected to each multiple. Hence, every time a selector switch attempts to extend a call o er any group of trunks'representedby any particular level of terminals, and finds all trunks of such group engaged, the magnet 7 5 individual to that level. is actuated to produce a count upon the device 76. The information atlordcd in this manner readily shows the exact number of calls that are being lost to any group of trunks in the system, due to the fact that all trunks of such group are busy when the calls are made.

If it is discovered that a certain group of trunks is losing a large number of its calls, this indicates that the particular group of. say 100, subscribers lines served thereby, contains a relatively large number of lines that are occupying the use of said trunk group as called lines a large portion of the time. Having secured this information, it then ren'iains to determine the exact location of such lines so that they maybe properly redistrilnited. This is accon'iplished by the registering devices associated with the con- 1% nector switches, for. as already explained.

a record is obtained thereby of every call made into each small group of lines represented by a level of the connector switches.

By thus isolating the abnormally busy l mes down to the particular small group or groups of lines. it is then an easy matter to remedy the evil by an adequate redistribution.

it is obvious that the registering devices 1243 employed at: the connector switches need not be permal'iently associated therewith. In practice a portable group often register magnets d3, could be associated withthe particular group of connectors that is de E25 sired to be observed.

What is claimed is:

1. in a telephone exchange system, subscribers lines. selector and connector switches for establishing a connection be- 3 tween said lines, means associated with the selector switches for recording the number of calls that fail to secure service due to all of the. connectors being simultaneously busy, and means associated with said connector switches for recording the number of calls extended to a group of subscribers lines.

2.1a a telephone exchange system, subscribers lines, selector and connector switches for establishing a connection between .said lines, registering devices associated with the selector switches adapted to register the number of calls failing to secure service due to all the connectors apportioned to such calls being busy, and. registering means associated with said busy connector switches for recording the number of calls extended to a group of subscribersv lines,

3'. In a telephone exchange system, sub scribers lines, selector and connector switches forestablishing a connection be tween said lines, said connectors being arranged in groups, a group of trm'ilrsextending from said selectors to each group of connectors, a registering device associated with each group of trunks and operated by the selector switches to register the number of calls lost by any of said groups due to all the connectors apportioned to such group being busy at the time the calls were made,

and registering device's adapted to be associated with anysuch group of busy connecs tors and operated thereby for registering the number of calls extended to said group.

4. In a telephone exchange system, selector and connector switches, a group of subscribers lines arranged in sub-groups and terminating in said connector switches,

m ans including said selectors andconnectors for connecting a calling line to any line in said group, means operated by the selector switches for'detecting the number of unsuccessful calls due to the simultaneous busy condition of all connectors apportioned to said group, and means associated with each of said sub-groups of lines for recording the number of calls to said sub-group.

5.. In a telephone system, subscribers lines, selector switches havin terminal banks arrangedin levels and with said banks, groups of connector switches having terminal banks arranged in rushes coiiperating neriasa the trunk seized over any level of said connector terminals to connect with a desired line therein, a registering device associated with each selector level and operated each time a selector finds all the connectors of a group busy, and a registerin device associated with each level of sue a busy connector group for counting the total number of calls made into said level.

6. In a telephone system, telephone lines divided into groups and sub-groups, selec tive switches for interconnecting said lines, means for detecting the abnormally busy condition of a group of said lines comprising means for counting the number of unsuccessful calls directed through said switches toward said group, and means for counting the number of successful calls directed through said switches toward each sub-group of said group.

7. In a telephone system, telephone lines, selective switches for interconnecting said lines, and means associated with said switches for recording the number of times said selective switches are actuated during the time all availablepaths leading from said switches are simultaneously busy.

.8. In a telephone system, telephone lines, an automatic switch for interconnecting said lines, said switch having brushes and actuatinp; means therefor, groupsof trunks appearing in terminals at said switch, an-additional set of terminals associated with the switch and arranged to be engaged by one of said brushes each time the switch fails to extend a call into any of said groups due to the simultaneous busy condition of all thetrunks in such group, and registering means operated each time said brush engages said additional set of terminals.

In witness whereof, I hereunto subscribe my name this 30th day of July A. D., 1917.

HENRY r. CLAUSEN. 

